Stents are prosthetic devices typically intraluminally placed by a catheter within a vein, artery, or other tubular body organ for treating conditions such as, occlusions, stenoses, aneurysms, dissection, or weakened, diseased, or abnormally dilated vessels or vessel walls, by expanding vessels or by reinforcing vessel walls. Stents can improve angioplasty results by preventing elastic recoil and remodeling of the vessel wall and treating dissections in blood vessel walls caused by balloon angioplasty of coronary arteries.
Stents are typically tubular and expandable from a collapsed state to an expanded state. In a typical operation to implant a stent, the stent is initially configured in the collapsed state, with a cross-sectional size sufficiently small for ease of passage to the intended site. After the stent reaches the intended site, the stent is typically deformed to increase its cross-sectional size to fully engage the stent with the surrounding tissues. The stent thereafter remains in place in the expanded state.
In some cases, stents are impregnated with drugs, i.e., therapeutic agents, to be released over time to treat various conditions. Drugs are typically dispersed in porous drug reservoir layers formed on the surfaces of metallic stent bodies. Bonding between the drug reservoir layers and the stent bodies is of significant concern as the stents typically undergo significant deformation during deployment, and detachment of the drug reservoir layers from the stent bodies would generally be undesirable.
While conventional stent technology is relatively well developed, technologies related to drug-delivering stents are still being developed.